Surfboard fin

ABSTRACT

A t-shaped, hydrodynamic fin (“t-fin”) for surfboards designed to maximize performance and maneuverability of the surfboard by creating, in conjunction with two vertical side fins, two chambers to funnel and control the flow of water. The crosspiece of the t-fin is parallel to the surfboard and is horizontal when the surfboard is level from side to side. But also functions as a vertical fin when the board is tilted sideways (in either direction) and the side fins lose their verticality. The t-fin enhances surfboard maneuverability by maintaining fin perpendicularity on the board at all times. The t-fin is fastened to the underside of the surfboard, at the stern, but a second t-fin may be fastened at the same time to the bow underside, to achieve a surfboard that can be used reversibly. T-fins are custom-made, shaped and contoured, and the crosspiece of the t-fin affixed, to achieve the desired hydrodynamic effect. T-fins utilize fin replacement systems, so that different designed t-fins (of varying degrees and profiles) may be used interchangeably with one another, but not limited to interchangeable fin systems. A fixed fin configuration (permanently attached) is sometimes desired.

SPECIFICATION

[0001] Invented is a fin which pertains to water planing devices,namely, a surfboard (a wave riding vehicle). The invented fin (locatedin the center rear position) works in conjunction with side fins, whichare in most cases, already existing on the surfboard. This newtechnology could, however, lend itself to custom placed side fins toachieve a different result. The invented fin is a vertical foil, withtwo bilaterally attached horizontal foils toward the vertical fin tip.These foils are forward leaned, to control the water flowing betweensaid horizontal foil, the vertical foil, the surfboard surface and theopposing side fin configuration. This creates two chambers (semienclosed) of water passing under the rear section of said surfboard. Thefin is constructed of, but not limited to, fiberglass or carbon fiber.First the vertical fin is constructed, currently in a mold, then setinto a jig, where the horizontal foils are attached at a desired angle.The horizontal foils are also made of fiberglass or carbon fiber, andthey also may be handcrafted or molded pieces. The horizontal foils areaffixed to the vertical foil using a common bonding method (in surfboardmanufacturing), using fiberglass rope at the seams, and layingfiberglass cloth over the rope and overlapping onto the desired adheredsurfaces. The result is an inverted “T” shaped fin. This fin, wheninstalled in the center rear position of a common modern three finsurfboard, will result in two semi controlled chambers of water passingunder the rear section of said surfboard. Furthermore, if this inventedfin were to travel backward it would provide lift, because of thereverse travel of the forward leaned horizontal foils. Thischaracteristic lends itself to the ability to attach the same or similarfin configurations to both ends of the underside of a surfboard andachieve a surfboard that may be indiscriminately ridden without regardto nose and tail or front and rear. The forward mounted fin will providelift, while the rearward mounted fin will provide down force.

REFERENCES CITED U.S. Patent Documents

[0002] 5309859 May 1994 Miller 114/274 5152705 October 1992 Rock 441/74 5057045 October 1991 Myers 441/79  5062378 November 1991 Bateman 114/2744320546 March 1982 Knox 441/74 

Foreign Patent Documents

[0003] 2516472 May 1983 FR 441/79 2828859 January 1980 DE 441/74

BACKGROUND OF THE INVENTION

[0004] The present invention is related to water planing devices hereinreferred to as a surfboard, and particularly a surfboard havinghydrodynamic fin properties, which provide the surfboard with controlledchambers of water at the underside rear section of said surfboard, aswell as providing lift should the hydrodynamic fin travel backward. Thisfin may be used as a replacement for the center rear fin of a commonmodern multi-fin surfboard, to achieve this chambering effect withnegative lift properties. Furthermore, this fin when traveling backwardsprovides lift, should the surfer re-enter the breaking wave backward,with less incidence of submerging the tail of the backward travelingsurfboard. These properties allow said fin to be positioned, with thecomplementing side fin configurations, at both ends of a surf or planartype board, to achieve a surfboard capable of generating speed, on abreaking wave, with either end being used as the tail or rear section.Inherently surfboards generate their speed using the fin configurationat the rear of the surfboard. the forward mounted fin will then betraveling backwards, with the reverse traveling foils providing lift tothe forward section of said surfboard. A previous patent with down forcetechnology, U.S. Pat. No. 4,320,546, is a surfboard. This patentdescribes down force technology in the same area of the surfboard,however, is not using a side fin configuration to create a variablebetween the center fin and a vertical side fin. The side finconfiguration with horizontal foils in place on the center rear fin,does not create a complete enclosure, but the effects of chambering thewater under the surfboard are obvious when used and adjusted withdifferent fin sizes, profiles, angles, and placements. Furthermore, nopatent researched uses the same or similar type fin on the front andrear of a surfboard to achieve a lift and down force effectssimultaneously.

SUMMARY OF THE INVENTION

[0005] The invention comprises of a surfboard, having a planing hull,and a unique fin configuration characterized by a configurationconsisting of at least three vertical foils; one foil located on eachside toward the rear underside section and one vertical foil locatedfurther rearward in the center. This center rear vertical foil isconstructed with two symmetrically placed horizontal foils locatedtoward the fin tip. These horizontal foils are forward leaned to providedown force to the forward traveling surfboard, as well as lift for thetail, should the surfboard travel backward. This allows for theconfiguration to be applied to both ends of a surfboard, if desired, toachieve an omni-directional surfboard, or one that will be able to turnone hundred eighty degrees and continue to surf forward without loss offin propulsion. If a surfer decides to replace the center rear fin of acommon multi-fin surfboard, with the hydrodynamic fin, the benefits willbe extra grip of the existing side fins as well as having a foil thatmaintains verticality while the surfboard is executing a turn.Furthermore, the hydrodynamic fin's profile is lower than that of astandard common vertical foil. This gives the surfboard a looser feelwithout sacrificing speed or maneuverability and also facilitates intail-first re-entries, by providing positive lift due to the reversetraveling forward leaned horizontal foils.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006]FIG. 1 is a side and sectional rear bottom view of a conventionalmodern surfboard, using a three fin configuration. The arrow above thesurfboard depicts the direction of travel in which the surfboard iscapable of generating speed on a breaking wave.

[0007]FIG. 2 is a side and sectional rear bottom view of a conventionalmodern surfboard using the invented hydrodynamic fin in the center rearposition.

[0008]FIG. 3 is a side and bottom view of a surfboard using the inventedfin, with side fin configurations, on the forward and rearward sectionsof said surfboard. The arrow placed above the top surface of thesurfboard depicts the directions of travel in which the surfboard iscapable of generating speed on a breaking wave.

[0009]FIG. 4 is a perspective view of the bottom rear section of amodern surfboard 1 having a replaceable fin fixture system 4, whereinthe invented fin 3 is used to replace the center fin of saidconventional surfboard.

[0010]FIG. 5 is a side view of the invented hydrodynamic fin 3 with anarrow placed above the fin to depict the direction of travel to generatedown force.

[0011]FIG. 6 is a bottom view of the invented hydrodynamic fin 3depicting the profile of the horizontal foils 6.

[0012]FIG. 7 is a front view of the invented hydrodynamic fin 3,illustrating the horizontal foils 6 attached to the vertical foil 5.

DETAILED DESCRIPTION

[0013]FIG. 1 is a side and bottom rear sectional view of a conventionalmodern surfboard using a three fin configuration. The illustrationdepicts that there is a top and bottom surface of the surfboard, andthat the vertical fins are located on the bottom rear section of thesurfboard. The arrow placed above the top surface of the surfboarddepicts the direction of travel in which the surfboard is capable ofgenerating speed on a breaking wave. The bottom rear sectional viewillustrates the positioning of the three vertical foils.

[0014]FIG. 2 is a side and sectional bottom rear view of a conventionalsurfboard, with the invented hydrodynamic fin replacing the commonvertical foil. The bottom rear sectional illustrates the profile of thehorizontal foils attached to the center rear vertical foil. Theillustration also depicts that there are two vertical foils placedforward and toward the sides of the bottom rear section of thesurfboard.

[0015]FIG. 3 is a side and bottom view of an exemplary embodiment ofthis invented fin. When accompanied by the vertical side fins, andmounted on the forward and rearward sections of a surfboard, enables thesurfboard to generate speed with the rearward placed fin configuration,while the reverse traveling forward fin provides lift, due to thereverse travel of the otherwise negative lift inducing horizontal foils.The arrow placed above the top of the surface of the side view indicatesthe surfboard is capable of generating speed in two directions. Thebottom view illustrates the cluster of the fin configurations located ateach end of the surfboard.

[0016]FIG. 4 is a perspective view of the bottom rear section of aconventional surfboard 1, generally constructed from shaping closed cellfoam and encasing the shape with fiberglass and polystyrene or epoxyresins, and fitted with a common fin fixture system 4, i.e. U.S. Pat.No. 5,464,359, which is a molded plastic receptacle which receives a fin2 manufactured with a male counterpart or tab. The fin is held in placeby a set screw, located in the receptacle 4. The invented hydrodynamicfin 3 is shown to replace the vertical profile fin 2 in the rear centerposition.

[0017]FIG. 5 is a side view of the invented hydrodynamic fin 3. This finis constructed with either fiberglass, carbon fiber, or molded plastic.Currently, the vertical foil 5 is made by using a pre-cut piece of balsawood for core. This is encased by carbon fiber cloth and placed in amold, which is then injected with polystyrene resin. The horizontalfoils are made in the same manner. The vertical foil is then placed in ajig, which will hold the horizontal foils 6 at a desired angle forattachment to the vertical foil. The hydrodynamic fin 3, may also bemanufactured using a four piece mold and injected with plastic. Thehydrodynamic fin 3 may be manufactured to fit in receptacles asillustrated in FIG. 4, or manufactured to be permanently attached to thesurfboard (the plastic fin excluded). Fiberglass and/or carbon fiber arepreferred for permanently placed fins. In this case the vertical foil ismade without a male counterpart to the receptacle, and fastened to thesurfboard before the installation of the horizontal foils. This allowsfor a stronger assembly. It is possible, however, to attach aprefabricated hydrodynamic fin by means of fiberglass cloth and strandsof fiberglass rope, which is currently the most popular way ofpermanently affixing fins to a fiberglass surfboard. The vertical foil 5extends arcuately downward and rearward with the radius decreasingtoward the trailing edge. The horizontal foils 6 are attachedbilaterally toward the vertical fin tip, and leaned forward to anindeterminate number, depending on the desired effect. A neutral finwould have horizontal foils 6 placed with an equal distance betweensurfboard to leading edge and surfboard to trailing edge. A negativelift fin would have a lesser number from surfboard to trailing edge asopposed to the measurement from surfboard to leading edge. The effectsof a neutral foil are noticeable. However, some down force is usuallydesired. The arrow above the vertical foil 5 indicates forward.

[0018]FIG. 6 is a bottom view of the hydrodynamic fin 3 wherein thevertical foil 5 is joined with the horizontal foils 6 mountedsymmetrically on opposing sides. The horizontal foils 6 arcuately extendrearward with the trailing edge being somewhat arcuately relieved. Thearrow in the diagram indicates forward.

[0019]FIG. 7 is a front view of the hydrodynamic fin 3, wherein thevertical foil 5 is joined with the horizontal foils 6 locatedbilaterally toward the vertical foil 5 fin tip. The illustrationindicates a slight forward lean of the horizontal foils 6. This downforce angle adjusts the amount of water traveling between the side fins2, horizontal foils 6, vertical foils and surfboard bottom. 1. Thisangle also induces a faster turning surfboard. This reaction takes placewhen the maneuvering surfboard turns, it tilts, causing the horizontalfoils 6 to tilt toward vertical. When influenced by a forward leanedfoil, this causes or facilitates a sharper or tighter turn.

I claim:
 1. A t-fin for use dorsally at the centerline of the undersideof the surfboard (or planar-type board) that (a) is custom-made,-shaped, -contoured and -designed to achieve the desired hydrodynamiceffect; (b) consists of a cross-piece attached to a (conventional)vertical tail fin (frontally appearing like an inverted t) with theleading edge of the crosspiece angled (in relation to trailing edge) atfixed, intermediate degrees, to achieve the desired hydrodynamic effect;and (c) utilizes a standard plug-in system for attaching the t-fin tothe surfboard, so that the custom-built t-fins (with crosspieces ofvarying angles) may be used interchangeably with one another.
 2. A t-finas claimed in No. 1 above, used in conjunction with two vertical, sidefins, in a 3-fin configuration that (a) is positioned to form twochambers that funnel the flow of water; (b) maintains finperpendicularity at all times, including when the surfboard is tiltedsideways; and (c) keeps the trailing end of the surfboard (where thefins are attached) from lifting off the surface of the water as thesurfboard moves forward.
 3. A t-fin, as claimed in No. 1 above (or a3-fin configuration, as claimed in No. 2 above), used in conjunctionwith a second t-fin (or a second 3-fin configuration), each t-fin (or3-fin configuration) attached to opposite ends of the surfboard, facingthe other, that allows the surfboard to be used reversibly.